This invention is directed to a pulsation damper for use in high pressure fluid systems. More particularly, it relates to a pulsation damper that will combine the flow from two separate high pressure fluid discharge lines associated with an air-conditioning system.
Pressure pulses are frequently encountered in high pressure fluid systems. As an example of a prior art high pressure fluid system, a compressor for use in air-conditioning system for an automobile is illustrated in FIG. 1. Compressor assembly 20 is mounted in housing 21 and has swash plate 22 that reciprocates two opposed pistons 24 and 26 in cylinders 25 and 27. Disc spring biased discharge valves 28 and 30 are pinned to a valve head within housing 21 at 29 and 31, respectively, and regulate the flow of pressurized refrigerant from cylinders 25 and 27. There may be three or more of the illustrated opposed piston arrangements spaced circumferentially about housing 21. As is well known, these three piston arrangements serially reciprocate out of phase from each other due to the swash plate 22.
Pistons 24 and 26 reciprocate to compress fluid within cylinders 25 and 27. When the fluid pressure reaches a predetermined value, the pressure within cylinders 25 and 27 will overcome the spring force of valves 28 and 30.
Compressor assembly 20, at the point illustrated in FIG. 1, has piston 24 discharging pressurized fluid from cylinder 25, through valve 28 and into a first discharge line 32. At the same time, piston 26 is discharging pressurized fluid from cylinder 27, through discharge valve 30 and into a second discharge line 34. A line 35 conducts fluid forwardly from first discharge line 32. An outlet 36 is disposed at a downstream end of both the first and second discharge lines 32 and 34 and receives fluid from both discharge lines. Outlet 36 is defined by an opening 37. A sealed connection conducts fluid from outlet 36 downstream in the air conditioning system.
Due to the reciporcating nature of this type of compressor, and the fact that valves 28 and 30 open only when a predetermined pressure is reached within cylinders 25 and 27, the resulting pressure at outlet 36 is seen as a series of pulses. As illustrated in FIG. 2, a pressure curve 38 for compressor assembly 20 has peaks and valleys that will result in undesirable drum-like noises during operation of the compressor assembly 20. The pressure curve 38 oscillates about a center line 39 that is the desired final pressure for the outlet 36. Each pulse, or oscillation, is associated with the discharge of one of the five opposed piston arrangements. Since the opposed pistons 24 and 26 may be both discharging at the same time, depending on the number of opposed piston arrangements used, the magnitude of the pulse may be increased.
In an idealized system, the pulses above and below the center line 39 would be eliminated and the pressure curve would approximate the center line 39. Various types of pulsation dampers have been employed to reduce the pulses within pressure curve 38. These prior art pulsation dampers have usually been relatively complex and expensive. They frequently require complicated attachments and housings.
The prior art pulsation dampers may be downstream of the compressor housing, connected by a hose to the compressor outlet and by a second hose to the condenser. Thus, these prior art pulsation dampers required four connection points. In high pressure system it is preferable to have as few connection points as possible.
In addition, the prior art pulsation dampers located downstream from the compressor assembly housing 21 add to the overall size of the system. It is a consideration in the design of any modern automobile system that all the components be as physically small as possible to make the most optimal use of available space.
U.S. Pat. Nos. 4,790,727 and 4,820,133 both disclose compressors as described above, in which a pulse damper is inserted in a compressor housing outlet. While this does provide several benefits, the disclosed pulse damper still has some disadvantages. In particular, the disclosed pulse damper is generally D-shaped in cross section with the flat side being received against a portion of the compressor housing. Thus, there is only flow over this pulse damper for approximately 180.degree.. Also, the outer periphery of this pulse damper is smooth and has no flow directing means. Lastly, this pulse damper passes through the valve plate of the compressor, but there is a substantial clearance between the pulse damper and the valve plate. Since there is only flow over 180.degree., there is no flow directing means, and there is a relatively large clearance between the valve plate and the pulse damper, the flow from one fluid passage is not directed into the flow from the other fluid passage such that pulses in the two flows are substantially reduced.
It is therefore an object of the present invention to disclose an improved pulsation damper that is simple to manufacture, relatively inexpensive and useful as a retro-fit into existing compressors.